The Helium migration to the Solana Mainnet was completed May 22, 2023.
This did not change the HNT coin to SOL, instead it transfers Helium to the Solana network. You will still see HNT in your wallet, but any transactions on it will be done on the Solana network.
Warning: Any saved wallet addresses for HNT that you've used in the past to send HNT may no longer work. If in doubt, test first with a small amount.